1. Field of the Invention
The present invention relates to an absorbent article, such as a sanitary napkin, and the like, having a good sealing performance and fitting property, in which a liquid prevention groove is formed to prevent separation of a compressed part.
2. Related Art
Conventionally, an absorbent article is generally known to include an absorbent layer, a liquid permeable top sheet covering the surface of a wearer's skin, a liquid impermeable back sheet covering the surface of the absorbent layer on the side of the wearer's clothing. Such an absorbent article is generally worn in a state in which a back sheet is bonded through a pressure sensitive adhesion layer to the inner surface of the clothing in the crotch region of an undergarment. A liquid impermeable groove is formed through compression by continuously applying pressure to bond the top sheet and the absorbent layer, and to prevent leakage by controlling the once absorbed body fluid from dispersing and at the same time giving a wearer a better fitted feeling.
In this liquid-proof groove, an absorbent layer is formed by surrounding a predetermined region in the absorbent layer so that the liquid absorbed by the absorbent layer does not flow out. As for the absorbent article having a shape extended in a longitudinal direction, the shape of the liquid-proof groove may be substantially elliptical or a modified shape thereof. This substantially elliptical absorbent article is curved at the edges extending in the longitudinal direction to form an end at the far end of this curve, which projects outward in the longitudinal direction.
Since an absorbent layer is usually a material having elasticity, a compressed portion and the vicinity thereof have resiliency so that the absorbent layer recovers from a compressed state back to an original state, so that force acts in a direction tending to separate the compressed portion.
Here, a plurality of the liquid-proof grooves are formed in a widthwise direction by surrounding an absorbent layer as described above. In other words, a top sheet and the absorbent layer are held together by compression at multiple sites in the widthwise direction. However, at the end projected outwardly in a longitudinal direction with the substantially elliptical shape as described above, since in practice they are held together by compression at one point, separation can easily occur in comparison with the compressed portion in the other liquid-proof grooves.
In addition, in response to a wearer's feeling on wearing this absorbent article and desirable liquid-proof effects, various other absorbent articles have been suggested, in which a plurality of the liquid-proof grooves are formed. However, when a plurality of the liquid-proof grooves are formed as thus described, for example, when a large number of the liquid-proof grooves are present in a widthwise direction of the absorbent article, the pressure exerted on the compressed portion, formed by a predetermined compression process, becomes insufficient, while causing the depth of the liquid-proof grooves to become shallow, making separation occur even more easily. Separation of the compressed portion in the liquid-proof grooves lowers leakage prevention performance and wearability.
Furthermore, for example, an absorbent article described in Japanese Patent Application, Laid Open No. 2001-8971 has a liquid-proof grooves without being shallow, which are formed by widening the width of the liquid-proof grooves in a region with two or fewer liquid-proof grooves in the widthwise direction, by reducing the width of the liquid-proof grooves in a region with three or more liquid-proof grooves in the widthwise direction, and by building up a sufficient pressure that is added to the compressed portion formed by a compression process.